LWBK1006-13 LWW-Govindan-Review November 24, 2011 11:22
Chapter 13•Cancer Screening 145ANSWERS
Answer 13.1. The answer is A.
Lead-time bias is the interval between the diagnosis of disease at screen-
ing and when it would have been detected because of the development of
symptoms. Length bias is the overrepresentation among screen-detected
cases of those with a long preclinical period (thus, less rapidly fatal), lead-
ing to the incorrect conclusion that screening was beneficial. Volunteers
who choose to participate in screening programs are likely to be differ-
ent from the general population in ways that affect survival. They may
be more compliant or may have healthier habits. Conversely, they may
volunteer because they think they are at higher risk for disease.Answer 13.2. The answer is A.
Primary prevention refers to the prevention of disease, such as the removal
of colon polyps to prevent the development of colon cancer. Secondary
prevention refers to the identification of disease at an early asymptomatic
stage through screening. Case finding occurs when a patient with symp-
tomatic disease presents to a physician for evaluation.Answer 13.3. The answer is D.
Primary prevention refers to the prevention of disease, such as the removal
of colon polyps to prevent the development of colon cancer. Secondary
prevention refers to the identification of disease at an early asymptomatic
stage through screening. Case finding occurs when a patient with symp-
tomatic disease presents to a physician for evaluation.Answer 13.4. The answer is B.
Primary prevention refers to the prevention of disease, such as the removal
of colon polyps to prevent the development of colon cancer. Secondary
prevention refers to the identification of disease at an early asymptomatic
stage through screening. Case finding occurs when a patient with symp-
tomatic disease presents to a physician for evaluation.Answer 13.5. The answer is A.
Chronic gastroesophageal reflux disease is associated with increased
risk for esophageal cancer. Plummer-Vinson syndrome is associated with
increased risk of squamous cell carcinoma of the esophagus. Screening
upper endoscopy or aggressive antireflux therapy for Barrett’s esophagus
has not been shown to decrease the risk for esophageal cancer.Answer 13.6. The answer is C.
The sensitivity of a test reflects its ability to detect a known disease, and
the specificity reflects the ability of a test to give a normal result when the
disease is known to be absent. From the point of view of the clinician, the